draft-ietf-mmusic-data-channel-sdpneg-11.txt   draft-ietf-mmusic-data-channel-sdpneg-12.txt 
MMUSIC K. Drage, Ed. MMUSIC K. Drage, Ed.
Internet-Draft M. Makaraju Internet-Draft M. Makaraju
Intended status: Standards Track Nokia Intended status: Standards Track Nokia
Expires: July 19, 2017 J. Stoetzer-Bradler Expires: September 19, 2017 J. Stoetzer-Bradler
R. Ejzak R. Ejzak
J. Marcon J. Marcon
Unaffiliated Unaffiliated
January 15, 2017 March 27, 2017
SDP-based Data Channel Negotiation SDP-based Data Channel Negotiation
draft-ietf-mmusic-data-channel-sdpneg-11 draft-ietf-mmusic-data-channel-sdpneg-12
Abstract Abstract
The Real-Time Communication in WEB-browsers (RTCWeb) working group is The Real-Time Communication in WEB-browsers (RTCWeb) working group is
charged to provide protocols to support direct interactive rich charged to provide protocols to support direct interactive rich
communications using audio, video, and data between two peers' web- communications using audio, video, and data between two peers' web-
browsers. For the support of data communication, the RTCWeb working browsers. For the support of data communication, the RTCWeb working
group has in particular defined the concept of bi-directional data group has in particular defined the concept of bi-directional data
channels over SCTP (Stream Control Transmission Protocol), where each channels over SCTP (Stream Control Transmission Protocol), where each
data channel might be used to transport other protocols, called data channel might be used to transport other protocols, called
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on July 12, 2017. This Internet-Draft will expire on September 19, 2017.
Copyright Notice Copyright Notice
Copyright (c) 2017 IETF Trust and the persons identified as the Copyright (c) 2017 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
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5.1.2. Other Media Level Attributes . . . . . . . . . . . . 10 5.1.2. Other Media Level Attributes . . . . . . . . . . . . 10
5.1.2.1. dcsa Attribute . . . . . . . . . . . . . . . . . 10 5.1.2.1. dcsa Attribute . . . . . . . . . . . . . . . . . 10
5.1.2.2. dcsa Multiplexing Category . . . . . . . . . . . 12 5.1.2.2. dcsa Multiplexing Category . . . . . . . . . . . 12
5.2. Procedures . . . . . . . . . . . . . . . . . . . . . . . 12 5.2. Procedures . . . . . . . . . . . . . . . . . . . . . . . 12
5.2.1. Managing Stream Identifiers . . . . . . . . . . . . . 12 5.2.1. Managing Stream Identifiers . . . . . . . . . . . . . 12
5.2.2. Negotiating Data Channel Parameters . . . . . . . . . 13 5.2.2. Negotiating Data Channel Parameters . . . . . . . . . 13
5.2.3. Opening a Data Channel . . . . . . . . . . . . . . . 14 5.2.3. Opening a Data Channel . . . . . . . . . . . . . . . 14
5.2.4. Closing a Data Channel . . . . . . . . . . . . . . . 16 5.2.4. Closing a Data Channel . . . . . . . . . . . . . . . 16
5.2.5. Various SDP Offer/Answer Scenarios and Considerations 17 5.2.5. Various SDP Offer/Answer Scenarios and Considerations 17
6. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . 18 6. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . 18
7. Security Considerations . . . . . . . . . . . . . . . . . . . 21 7. Security Considerations . . . . . . . . . . . . . . . . . . . 20
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 21 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 20
8.1. Subprotocol Identifiers . . . . . . . . . . . . . . . . . 22 8.1. Subprotocol Identifiers . . . . . . . . . . . . . . . . . 21
8.2. New SDP Attributes . . . . . . . . . . . . . . . . . . . 22 8.2. New SDP Attributes . . . . . . . . . . . . . . . . . . . 21
8.2.1. dcmap . . . . . . . . . . . . . . . . . . . . . . . . 22 8.2.1. dcmap . . . . . . . . . . . . . . . . . . . . . . . . 21
8.2.2. dcsa . . . . . . . . . . . . . . . . . . . . . . . . 23 8.2.2. dcsa . . . . . . . . . . . . . . . . . . . . . . . . 22
8.3. New Usage Level . . . . . . . . . . . . . . . . . . . . . 23 8.3. New Usage Level . . . . . . . . . . . . . . . . . . . . . 22
9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 24 9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 23
10. CHANGE LOG . . . . . . . . . . . . . . . . . . . . . . . . . 24 10. CHANGE LOG . . . . . . . . . . . . . . . . . . . . . . . . . 23
10.1. Changes against 'draft-ietf-mmusic-data-channel- 10.1. Changes against 'draft-ietf-mmusic-data-channel-
sdpneg-10' . . . . . . . . . . . . . . . . . . . . . . . 24 sdpneg-11' . . . . . . . . . . . . . . . . . . . . . . . 23
10.2. Changes against 'draft-ietf-mmusic-data-channel- 10.2. Changes against 'draft-ietf-mmusic-data-channel-
sdpneg-09' . . . . . . . . . . . . . . . . . . . . . . . 24 sdpneg-10' . . . . . . . . . . . . . . . . . . . . . . . 23
10.3. Changes against 'draft-ietf-mmusic-data-channel- 10.3. Changes against 'draft-ietf-mmusic-data-channel-
sdpneg-08' . . . . . . . . . . . . . . . . . . . . . . . 25 sdpneg-09' . . . . . . . . . . . . . . . . . . . . . . . 23
10.4. Changes against 'draft-ietf-mmusic-data-channel- 10.4. Changes against 'draft-ietf-mmusic-data-channel-
sdpneg-07' . . . . . . . . . . . . . . . . . . . . . . . 25 sdpneg-08' . . . . . . . . . . . . . . . . . . . . . . . 24
10.5. Changes against 'draft-ietf-mmusic-data-channel- 10.5. Changes against 'draft-ietf-mmusic-data-channel-
sdpneg-06' . . . . . . . . . . . . . . . . . . . . . . . 26 sdpneg-07' . . . . . . . . . . . . . . . . . . . . . . . 25
10.6. Changes against 'draft-ietf-mmusic-data-channel- 10.6. Changes against 'draft-ietf-mmusic-data-channel-
sdpneg-05' . . . . . . . . . . . . . . . . . . . . . . . 26 sdpneg-06' . . . . . . . . . . . . . . . . . . . . . . . 25
10.7. Changes against 'draft-ietf-mmusic-data-channel- 10.7. Changes against 'draft-ietf-mmusic-data-channel-
sdpneg-04' . . . . . . . . . . . . . . . . . . . . . . . 27 sdpneg-05' . . . . . . . . . . . . . . . . . . . . . . . 25
10.8. Changes against 'draft-ietf-mmusic-data-channel- 10.8. Changes against 'draft-ietf-mmusic-data-channel-
sdpneg-03' . . . . . . . . . . . . . . . . . . . . . . . 27 sdpneg-04' . . . . . . . . . . . . . . . . . . . . . . . 26
10.9. Changes against 'draft-ietf-mmusic-data-channel- 10.9. Changes against 'draft-ietf-mmusic-data-channel-
sdpneg-02' . . . . . . . . . . . . . . . . . . . . . . . 29 sdpneg-03' . . . . . . . . . . . . . . . . . . . . . . . 27
10.10. Changes against 'draft-ietf-mmusic-data-channel- 10.10. Changes against 'draft-ietf-mmusic-data-channel-
sdpneg-01' . . . . . . . . . . . . . . . . . . . . . . . 30 sdpneg-02' . . . . . . . . . . . . . . . . . . . . . . . 28
10.11. Changes against 'draft-ietf-mmusic-data-channel- 10.11. Changes against 'draft-ietf-mmusic-data-channel-
sdpneg-00' . . . . . . . . . . . . . . . . . . . . . . . 32 sdpneg-01' . . . . . . . . . . . . . . . . . . . . . . . 29
10.12. Changes against 'draft-ejzak-mmusic-data-channel- 10.12. Changes against 'draft-ietf-mmusic-data-channel-
sdpneg-02' . . . . . . . . . . . . . . . . . . . . . . . 35 sdpneg-00' . . . . . . . . . . . . . . . . . . . . . . . 31
10.13. Changes against '-01' . . . . . . . . . . . . . . . . . 36 10.13. Changes against 'draft-ejzak-mmusic-data-channel-
10.14. Changes against '-00' . . . . . . . . . . . . . . . . . 36 sdpneg-02' . . . . . . . . . . . . . . . . . . . . . . . 34
11. References . . . . . . . . . . . . . . . . . . . . . . . . . 36 10.14. Changes against '-01' . . . . . . . . . . . . . . . . . 35
11.1. Normative References . . . . . . . . . . . . . . . . . . 36 10.15. Changes against '-00' . . . . . . . . . . . . . . . . . 35
11.2. Informative References . . . . . . . . . . . . . . . . . 37 11. References . . . . . . . . . . . . . . . . . . . . . . . . . 35
11.1. Normative References . . . . . . . . . . . . . . . . . . 35
11.2. Informative References . . . . . . . . . . . . . . . . . 36
Appendix A. Generic Data Channel Negotiation Aspects When Not Appendix A. Generic Data Channel Negotiation Aspects When Not
Using DCEP . . . . . . . . . . . . . . . . . . . . . 38 Using DCEP . . . . . . . . . . . . . . . . . . . . . 37
A.1. Stream Identifier Numbering . . . . . . . . . . . . . . . 39 A.1. Stream Identifier Numbering . . . . . . . . . . . . . . . 38
A.2. Generic Data Channel Negotiation Not Using DCEP . . . . . 39 A.2. Generic Data Channel Negotiation Not Using DCEP . . . . . 38
A.2.1. Overview . . . . . . . . . . . . . . . . . . . . . . 39 A.2.1. Overview . . . . . . . . . . . . . . . . . . . . . . 38
A.2.2. Opening a Data Channel . . . . . . . . . . . . . . . 39 A.2.2. Opening a Data Channel . . . . . . . . . . . . . . . 39
A.2.3. Closing a Data Channel . . . . . . . . . . . . . . . 40 A.2.3. Closing a Data Channel . . . . . . . . . . . . . . . 40
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 41 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 40
1. Introduction 1. Introduction
The RTCWeb working group has defined the concept of bi-directional The RTCWeb working group has defined the concept of bi-directional
data channels running on top of the Stream Control Transmission data channels running on top of the Stream Control Transmission
Protocol (SCTP). RTCWeb allows applications to use data channels. Protocol (SCTP). RTCWeb allows applications to use data channels.
RTCWeb defines an in-band Data Channel Establishment Protocol (DCEP), RTCWeb defines an in-band Data Channel Establishment Protocol (DCEP),
however other in-band or out-of-band protocols may be used for however other in-band or out-of-band protocols may be used for
establishing data channels. Each data channel consists of paired establishing data channels. Each data channel consists of paired
SCTP streams sharing the same SCTP Stream Identifier. Data channels SCTP streams sharing the same SCTP Stream Identifier. Data channels
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data channel, and whether it is signaled in-band using DCEP or out- data channel, and whether it is signaled in-band using DCEP or out-
of-band using a non-DCEP protocol (or both). In particular, the SDP of-band using a non-DCEP protocol (or both). In particular, the SDP
offer generated by the RTCweb data channel stack includes no channel- offer generated by the RTCweb data channel stack includes no channel-
specific information. specific information.
This document defines SDP offer/answer negotiation procedures to This document defines SDP offer/answer negotiation procedures to
establish data channels for transport of well-defined subprotocols, establish data channels for transport of well-defined subprotocols,
to enable out-of-band negotiation. These procedures are based on to enable out-of-band negotiation. These procedures are based on
generic SDP offer/answer negotiation rules for SCTP based media generic SDP offer/answer negotiation rules for SCTP based media
transport as specified in [I-D.ietf-mmusic-sctp-sdp] for the SDP "m" transport as specified in [I-D.ietf-mmusic-sctp-sdp] for the SDP "m"
line proto values UDP/DTLS/SCTP and TCP/DTLS/SCTP. In future data line proto values UDP/DTLS/SCTP and TCP/DTLS/SCTP. In the future,
channels could be defined over other SCTP based protocols, such as data channels could be defined over other SCTP based protocols, such
SCTP over IP. However, corresponding potential other "m" line proto as SCTP over IP. However, corresponding potential other "m" line
values are not considered in this document. proto values are not considered in this document.
This document makes use of MSRP (Message Session Relay Protocol) in This document makes use of MSRP (Message Session Relay Protocol) and
many of the examples. It does not provide a complete specification BFCP (Binary Floor Control Protocol) in many of the examples. It
of how to negotiate the use of a data channel to transport MSRP. does not provide a complete specification of how to negotiate the use
Procedures specific to each subprotocol such as MSRP are documented of a data channel to transport MSRP. Procedures specific to each
elsewhere. The use of MSRP in some examples is only to show how the subprotocol such as MSRP are documented elsewhere. The use of MSRP
generic procedures described herein might apply to a specific in some examples is only to show how the generic procedures described
subprotocol. herein might apply to a specific subprotocol.
2. Conventions 2. Conventions
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119]. document are to be interpreted as described in [RFC2119].
3. Terminology 3. Terminology
This document uses the following terms: This document uses the following terms:
Data channel: A WebRTC data channel as specified in Data channel: A WebRTC data channel as specified in
[I-D.ietf-rtcweb-data-channel]. [I-D.ietf-rtcweb-data-channel].
Data channel stack: An entity which, upon application request, Data channel stack: An entity which, upon application request,
runs the data channel protocol to keep track of states, sending runs the data channel protocol to keep track of states, sending
and receive data. If the application is a browser based and receiving data. If the application is a browser based
JavaScript application then this stack resides in the browser. If JavaScript application then this stack resides in the browser. If
the application is a native application then this stack resides in the application is a native application then this stack resides in
the application and is accessible via some sort of APIs. the application and is accessible via some sort of APIs.
Data channel properties: Fixed properties assigned to a data Data channel properties: Fixed properties assigned to a data
channel at the time of its creation. Some of these properties channel at the time of its creation. Some of these properties
determine the way the data channel stack transmits data on this determine the way the data channel stack transmits data on this
channel (e.g., stream identifier, reliability, order of channel (e.g., stream identifier, reliability, order of
delivery...). delivery...).
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Syntax: Syntax:
dcmap-value = dcmap-stream-id dcmap-value = dcmap-stream-id
[ SP dcmap-opt *(";" dcmap-opt) ] [ SP dcmap-opt *(";" dcmap-opt) ]
dcmap-opt = ordering-opt / subprotocol-opt / label-opt dcmap-opt = ordering-opt / subprotocol-opt / label-opt
/ maxretr-opt / maxtime-opt / priority-opt / maxretr-opt / maxtime-opt / priority-opt
; Either only maxretr-opt or maxtime-opt ; Either only maxretr-opt or maxtime-opt
; is present. ; is present.
dcmap-stream-id = 1*DIGIT dcmap-stream-id = 1*5DIGIT
ordering-opt = "ordered=" ordering-value ordering-opt = "ordered=" ordering-value
ordering-value = "true" / "false" ordering-value = "true" / "false"
subprotocol-opt = "subprotocol=" quoted-string subprotocol-opt = "subprotocol=" quoted-string
label-opt = "label=" quoted-string label-opt = "label=" quoted-string
maxretr-opt = "max-retr=" maxretr-value maxretr-opt = "max-retr=" maxretr-value
maxretr-value = "0" / integer maxretr-value = "0" / integer
; number of retransmissions, ; number of retransmissions,
; less than 2^32, ; less than 2^32,
; derived from 'Reliability Parameter' of ; derived from 'Reliability Parameter' of
; [I-D.ietf-rtcweb-data-protocol] ; [I-D.ietf-rtcweb-data-protocol]
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priority-opt = "priority=" priority-value priority-opt = "priority=" priority-value
priority-value = "0" / integer priority-value = "0" / integer
; unsigned integer value indicating the priority of ; unsigned integer value indicating the priority of
; the data channel, ; the data channel,
; less than 2^16, ; less than 2^16,
; derived from 'Priority' of ; derived from 'Priority' of
; [I-D.ietf-rtcweb-data-protocol] ; [I-D.ietf-rtcweb-data-protocol]
quoted-string = DQUOTE *(quoted-char / escaped-char) DQUOTE quoted-string = DQUOTE *(quoted-char / escaped-char) DQUOTE
quoted-char = SP / quoted-visible quoted-char = SP / quoted-visible
quoted-visible = %21 / %23-24 / %26-7E ; VCHAR without " or % quoted-visible = %x21 / %x23-24 / %x26-7E ; VCHAR without " or %
escaped-char = "%" HEXDIG HEXDIG escaped-char = "%" HEXDIG HEXDIG
DQUOTE = <from-RFC5234> DQUOTE = <from-RFC5234>
integer = <from-RFC4566> integer = <from-RFC4566>
Examples: Examples:
a=dcmap:0 a=dcmap:0
a=dcmap:1 subprotocol="BFCP";max-time=60000;priority=512 a=dcmap:1 subprotocol="BFCP";max-time=60000;priority=512
a=dcmap:2 subprotocol="MSRP";ordered=true;label="MSRP" a=dcmap:2 subprotocol="MSRP";ordered=true;label="MSRP"
a=dcmap:3 label="Label 1";ordered=false;max-retr=5;priority=128 a=dcmap:3 label="Label 1";ordered=false;max-retr=5;priority=128
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Usage Level: media Usage Level: media
Charset Dependent: no Charset Dependent: no
Syntax: Syntax:
dcsa-value = stream-id SP attribute dcsa-value = stream-id SP attribute
attribute = <from-RFC4566> attribute = <from-RFC4566>
Example: Example (other MSRP related SDP attributes are omitted for brevity):
a=dcsa:2 accept-types:text/plain a=dcsa:2 accept-types:text/plain
Note that the above reference to [RFC4566] defines where the Note that the above reference to [RFC4566] defines where the
attribute definition can be found; it does not provide any limitation attribute definition can be found; it does not provide any limitation
on support of attributes defined in other documents in accordance on support of attributes defined in other documents in accordance
with this attribute definition. Note however that not all SDP with this attribute definition. Note however that not all SDP
attributes are suitable as a "a=dcsa:" parameter. attributes are suitable as a "a=dcsa:" parameter.
[IANA-SDP-Parameters] contains the lists of IANA (Internet Assigned [IANA-SDP-Parameters] contains the lists of IANA (Internet Assigned
Numbers Authority) registered session and media level or media level Numbers Authority) registered session and media level or media level
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attributes are used in the same way as defined in the original attributes are used in the same way as defined in the original
subprotocol specification, also if the subprotocol is transported subprotocol specification, also if the subprotocol is transported
over a data channel and if the attribute is correspondingly embedded over a data channel and if the attribute is correspondingly embedded
in a "a=dcsa" attribute. in a "a=dcsa" attribute.
There may be cases, where the usage of a subprotocol related media There may be cases, where the usage of a subprotocol related media
level attribute depends on the subprotocol's transport protocol. In level attribute depends on the subprotocol's transport protocol. In
such cases the subprotocol related usage of the attribute is expected such cases the subprotocol related usage of the attribute is expected
to be described for the data channel transport. A data channel to be described for the data channel transport. A data channel
specific usage of a subprotocol attribute is expected to be specified specific usage of a subprotocol attribute is expected to be specified
in the same document, which registers the subprotocol's identifier in the same document, that registers the subprotocol's identifier for
for data channel usage as described in Section 8.1. data channel usage as described in Section 8.1.
5.1.2.2. dcsa Multiplexing Category 5.1.2.2. dcsa Multiplexing Category
The multiplexing category of the "a=dcsa:" attribute is SPECIAL. The multiplexing category of the "a=dcsa:" attribute is SPECIAL.
As the usage of multiple SCTP associations on top of a single DTLS As the usage of multiple SCTP associations on top of a single DTLS
association is outside the scope of [I-D.ietf-mmusic-sctp-sdp], no association is outside the scope of [I-D.ietf-mmusic-sctp-sdp], no
"a=dcsa:" attribute multiplexing rules are specified for the "a=dcsa:" attribute multiplexing rules are specified for the
UDP/DTLS/SCTP and TCP/DTLS/SCTP proto values. If future extensions UDP/DTLS/SCTP and TCP/DTLS/SCTP proto values. If future extensions
of [I-D.ietf-mmusic-sctp-sdp] define how to negotiate multiplexing of of [I-D.ietf-mmusic-sctp-sdp] define how to negotiate multiplexing of
skipping to change at page 13, line 21 skipping to change at page 13, line 21
5.2.2. Negotiating Data Channel Parameters 5.2.2. Negotiating Data Channel Parameters
Conveying a reliable data channel is achieved by including neither Conveying a reliable data channel is achieved by including neither
'max-retr' nor 'max-time' in corresponding SDP offer's or answer's 'max-retr' nor 'max-time' in corresponding SDP offer's or answer's
"a=dcmap:" attribute line. Conveying a partially reliable data "a=dcmap:" attribute line. Conveying a partially reliable data
channel is achieved by including only one of 'max-retr' or 'max- channel is achieved by including only one of 'max-retr' or 'max-
time'. By definition max-retr and max-time are mutually exclusive, time'. By definition max-retr and max-time are mutually exclusive,
so at most one of them MAY be present in the "a=dcmap:" attribute so at most one of them MAY be present in the "a=dcmap:" attribute
line. If a SDP offer contains both of these parameters then the line. If a SDP offer contains both of these parameters then the
receiver of such an SDP offer MUST reject the SDP offer. If a SDP receiver of such an SDP offer MUST reject the SDP offer. If a SDP
answer contains both of these parameters then the offerer MAY treat answer contains both of these parameters then the offerer MUST treat
it as an error and MAY assume the associated SDP offer/answer failed the associated SDP offer/answer failed and take appropriate recovery
and MAY take appropriate recovery actions. These recovery options actions. These recovery options are outside the scope of this
are outside the scope of this document. document.
The SDP answer SHALL echo the same subprotocol, max-retr, max-time, The SDP answer SHALL echo the same subprotocol, max-retr, max-time,
ordered parameters, if those were present in the offer, and MAY ordered parameters, if those were present in the offer, and MAY
include a label parameter. They MAY appear in any order, which could include a label parameter. They MAY appear in any order, which could
be different from the SDP offer, in the SDP answer. be different from the SDP offer, in the SDP answer.
When sending a subsequent offer or an answer, and for as long as the When sending a subsequent offer or an answer, and for as long as the
data channel is still open, the sender MUST replicate the same data channel is still open, the sender MUST replicate the same
information. information.
skipping to change at page 15, line 13 skipping to change at page 15, line 13
o Sends the SDP offer. o Sends the SDP offer.
The peer receiving such an SDP offer performs the following: The peer receiving such an SDP offer performs the following:
o Parses and applies the SDP offer, taking into account the o Parses and applies the SDP offer, taking into account the
considerations discussed in Section 5.2.5. considerations discussed in Section 5.2.5.
o Analyzes the channel parameters and subprotocol attributes to o Analyzes the channel parameters and subprotocol attributes to
determine whether to accept each offered data channel. determine whether to accept each offered data channel.
o For accepted data channels, it creates peer instances for the data o For accepted data channels, the agent MUST create peer instances
channels with the agent using the channel parameters described in for the data channels using the SCTP stream identifiers and
the SDP offer. Note that the agent is asked to create data channel parameters contained in the SDP offer.
channels with SCTP stream identifiers contained in the SDP offer
if the SDP offer is accepted.
o Generates an SDP answer. o Generates an SDP answer.
o Completes the SDP answer with the "a=dcmap:" and optional o Completes the SDP answer with the "a=dcmap:" and optional
"a=dcsa:" attributes needed for each SDP offer/answer negotiated "a=dcsa:" attributes needed for each SDP offer/answer negotiated
data channel, as described in Section 5.1 and in Section 5.2.2. data channel, as described in Section 5.1 and in Section 5.2.2.
o Sends the SDP answer. o Sends the SDP answer.
The agent receiving such an SDP answer performs the following: The agent receiving such an SDP answer performs the following:
skipping to change at page 16, line 33 skipping to change at page 16, line 31
(unless all data channels are being closed and the SCTP association (unless all data channels are being closed and the SCTP association
is no longer needed), since this would close the SCTP association and is no longer needed), since this would close the SCTP association and
impact all of the data channels. If the answerer accepts the SDP impact all of the data channels. If the answerer accepts the SDP
offer then the answerer MUST close those data channels whose offer then the answerer MUST close those data channels whose
"a=dcmap:" and "a=dcsa:" attribute lines were excluded from the "a=dcmap:" and "a=dcsa:" attribute lines were excluded from the
received SDP offer, unless those data channels were already closed, received SDP offer, unless those data channels were already closed,
and the answerer MUST also exclude the corresponding attribute lines and the answerer MUST also exclude the corresponding attribute lines
in the answer. In addition to that, the SDP answerer MAY exclude in the answer. In addition to that, the SDP answerer MAY exclude
other data channels which were closed but not yet communicated to the other data channels which were closed but not yet communicated to the
peer. So, the offerer MUST inspect the answer to see if it has to peer. So, the offerer MUST inspect the answer to see if it has to
close other data channels which are now not included in the answer. close other data channels that are now not included in the answer.
If a new SDP offer/answer is used to close data channels then the If a new SDP offer/answer is used to close data channels then the
data channel(s) SHOULD only be closed by the answerer/offerer after a data channel(s) SHOULD only be closed by the answerer/offerer after a
successful SDP answer is sent/received. successful SDP answer is sent/received.
This delayed closure is RECOMMENDED in order to handle cases where This delayed closure is RECOMMENDED in order to handle cases where
a successful SDP answer is not received, in which case the state a successful SDP answer is not received, in which case the state
of the session SHOULD be kept per the last successful SDP offer/ of the session SHOULD be kept per the last successful SDP offer/
answer. answer.
skipping to change at page 17, line 24 skipping to change at page 17, line 21
5.2.5. Various SDP Offer/Answer Scenarios and Considerations 5.2.5. Various SDP Offer/Answer Scenarios and Considerations
SDP offer has no "a=dcmap:" attributes. SDP offer has no "a=dcmap:" attributes.
* Initial SDP offer: No data channel is negotiated yet. The DTLS * Initial SDP offer: No data channel is negotiated yet. The DTLS
association and SCTP association is negotiated and, if agreed, association and SCTP association is negotiated and, if agreed,
established as per [I-D.ietf-mmusic-sctp-sdp]. established as per [I-D.ietf-mmusic-sctp-sdp].
* Subsequent SDP offer: All the SDP offer/answer negotiated data * Subsequent SDP offer: All the SDP offer/answer negotiated data
channels are expected be closed now. The DTLS/SCTP association channels are expected to be closed now. The DTLS/SCTP
remains open for SDP offer/answer or DCEP negotiation of data association remains open for SDP offer/answer or DCEP
channels. negotiation of data channels.
SDP answer has no "a=dcmap:" attributes. SDP answer has no "a=dcmap:" attributes.
* Initial SDP answer: Either the peer does not support "a=dcmap:" * Initial SDP answer: Either the peer does not support "a=dcmap:"
attributes or it rejected all the data channels. In either attributes or it rejected all the data channels. In either
case the offerer closes all the SDP offer/answer negotiated case the offerer closes all the SDP offer/answer negotiated
data channels that were open at the time of initial offer. The data channels that were open at the time of initial offer. The
DTLS association and SCTP association will still be setup. DTLS association and SCTP association will still be setup.
* Subsequent SDP answer: All the SDP offer/answer negotiated data * Subsequent SDP answer: All the SDP offer/answer negotiated data
channels are expected be closed now. The SCTP association channels are expected to be closed now. The SCTP association
remains open for future SDP offer/answer or DCEP negotiation of remains open for future SDP offer/answer or DCEP negotiation of
data channels. data channels.
SDP offer or answer has no "a=dcmap:" attributes but has "a=dcsa:" SDP offer or answer has no "a=dcmap:" attributes but has "a=dcsa:"
attributes. attributes.
* This is considered an error case. In this case the receiver of * This is considered an error case. In this case the receiver of
such an SDP offer or answer SHOULD ignore the "a=dcsa:" such an SDP offer or answer SHOULD ignore the "a=dcsa:"
attributes and SHOULD process the SDP offer or answer as per attributes and SHOULD process the SDP offer or answer as per
above case 'SDP offer has no "a=dcmap:" attributes' or case above case 'SDP offer has no "a=dcmap:" attributes' or case
skipping to change at page 19, line 4 skipping to change at page 18, line 26
entire "a=dcsa" attribute line. entire "a=dcsa" attribute line.
SDP offer or answer has an "a=dcsa" attribute, whose subprotocol SDP offer or answer has an "a=dcsa" attribute, whose subprotocol
attribute is known, but whose subprotocol attribute semantic is attribute is known, but whose subprotocol attribute semantic is
not known for the data channel transport case. not known for the data channel transport case.
* The receiver of such an SDP offer or answer SHOULD ignore this * The receiver of such an SDP offer or answer SHOULD ignore this
entire "a=dcsa" attribute line. entire "a=dcsa" attribute line.
6. Examples 6. Examples
SDP offer: SDP offer:
m=application 10001 UDP/DTLS/SCTP webrtc-datachannel m=application 10001 UDP/DTLS/SCTP webrtc-datachannel
c=IN IP4 10.10.10.1 c=IN IP4 192.0.2.1
a=max-message-size:100000 a=max-message-size:100000
a=sctp-port:5000 a=sctp-port:5000
a=setup:actpass a=setup:actpass
a=fingerprint:SHA-1 \ a=fingerprint:SHA-1 \
4A:AD:B9:B1:3F:82:18:3B:54:02:12:DF:3E:5D:49:6B:19:E5:7C:AB 4A:AD:B9:B1:3F:82:18:3B:54:02:12:DF:3E:5D:49:6B:19:E5:7C:AB
a=dtls-id:4a7565 a=dtls-id:4a7565
a=dcmap:0 subprotocol="BFCP";label="BFCP" a=dcmap:0 subprotocol="BFCP";label="BFCP"
SDP answer: SDP answer:
m=application 10002 UDP/DTLS/SCTP webrtc-datachannel m=application 10002 UDP/DTLS/SCTP webrtc-datachannel
c=IN IP4 10.10.10.2 c=IN IP4 192.0.2.2
a=max-message-size:100000 a=max-message-size:100000
a=sctp-port:5002 a=sctp-port:5002
a=setup:passive a=setup:passive
a=fingerprint:SHA-1 \ a=fingerprint:SHA-1 \
5B:AD:67:B1:3E:82:AC:3B:90:02:B1:DF:12:5D:CA:6B:3F:E5:54:FA 5B:AD:67:B1:3E:82:AC:3B:90:02:B1:DF:12:5D:CA:6B:3F:E5:54:FA
a=dtls-id:532d42 a=dtls-id:532d42
Figure 1: Example 1 Figure 1: Example 1
In the above example the SDP answerer rejected the data channel with In the above example the SDP answerer rejected the data channel with
stream id 0 either for explicit reasons or because it does not stream id 0 either for explicit reasons or because it does not
understand the "a=dcmap:" attribute. As a result the offerer will understand the "a=dcmap:" attribute. As a result the offerer will
close the data channel created with the SDP offer/answer negotiation close the data channel created with the SDP offer/answer negotiation
option. The SCTP association will still be setup over DTLS. At this option. The SCTP association will still be setup over DTLS. At this
point the offerer or the answerer may use DCEP negotiation to open point the offerer or the answerer may use DCEP negotiation to open
data channels. data channels.
SDP offer: SDP offer:
m=application 10001 UDP/DTLS/SCTP webrtc-datachannel m=application 10001 UDP/DTLS/SCTP webrtc-datachannel
c=IN IP4 10.10.10.1 c=IN IP4 192.0.2.1
a=max-message-size:100000 a=max-message-size:100000
a=sctp-port:5000 a=sctp-port:5000
a=setup:actpass a=setup:actpass
a=fingerprint:SHA-1 \ a=fingerprint:SHA-1 \
4A:AD:B9:B1:3F:82:18:3B:54:02:12:DF:3E:5D:49:6B:19:E5:7C:AB 4A:AD:B9:B1:3F:82:18:3B:54:02:12:DF:3E:5D:49:6B:19:E5:7C:AB
a=dtls-id:4a7565 a=dtls-id:4a7565
a=dcmap:0 subprotocol="BFCP";label="BFCP" a=dcmap:0 subprotocol="BFCP";label="BFCP"
a=dcmap:2 subprotocol="MSRP";label="MSRP" a=dcmap:2 subprotocol="MSRP";label="MSRP"
a=dcsa:2 accept-types:message/cpim text/plain a=dcsa:2 accept-types:message/cpim text/plain
a=dcsa:2 path:msrp://alice.example.com:10001/2s93i93idj;dc a=dcsa:2 path:msrp://alice.example.com:10001/2s93i93idj;dc
SDP answer: SDP answer:
m=application 10002 UDP/DTLS/SCTP webrtc-datachannel m=application 10002 UDP/DTLS/SCTP webrtc-datachannel
c=IN IP4 10.10.10.2 c=IN IP4 192.0.2.2
a=max-message-size:100000 a=max-message-size:100000
a=sctp-port:5002 a=sctp-port:5002
a=setup:passive a=setup:passive
a=fingerprint:SHA-1 \ a=fingerprint:SHA-1 \
5B:AD:67:B1:3E:82:AC:3B:90:02:B1:DF:12:5D:CA:6B:3F:E5:54:FA 5B:AD:67:B1:3E:82:AC:3B:90:02:B1:DF:12:5D:CA:6B:3F:E5:54:FA
a=dtls-id:532d42 a=dtls-id:532d42
a=dcmap:2 subprotocol="MSRP";label="MSRP" a=dcmap:2 subprotocol="MSRP";label="MSRP"
a=dcsa:2 accept-types:message/cpim text/plain a=dcsa:2 accept-types:message/cpim text/plain
a=dcsa:2 path:msrp://bob.example.com:10002/si438dsaodes;dc a=dcsa:2 path:msrp://bob.example.com:10002/si438dsaodes;dc
skipping to change at page 21, line 8 skipping to change at page 20, line 8
data channel for BFCP and both offerer and answerer may start using data channel for BFCP and both offerer and answerer may start using
the MSRP data channel (after the SCTP association is set up). The the MSRP data channel (after the SCTP association is set up). The
data channel with stream id 0 is free and can be used for future DCEP data channel with stream id 0 is free and can be used for future DCEP
or SDP offer/answer negotiation. or SDP offer/answer negotiation.
Continuing the example in Figure 2. Continuing the example in Figure 2.
Subsequent SDP offer: Subsequent SDP offer:
m=application 10001 UDP/DTLS/SCTP webrtc-datachannel m=application 10001 UDP/DTLS/SCTP webrtc-datachannel
c=IN IP4 10.10.10.1 c=IN IP4 192.0.2.1
a=max-message-size:100000 a=max-message-size:100000
a=sctp-port:5000 a=sctp-port:5000
a=setup:actpass a=setup:actpass
a=fingerprint:SHA-1 \ a=fingerprint:SHA-1 \
4A:AD:B9:B1:3F:82:18:3B:54:02:12:DF:3E:5D:49:6B:19:E5:7C:AB 4A:AD:B9:B1:3F:82:18:3B:54:02:12:DF:3E:5D:49:6B:19:E5:7C:AB
a=dtls-id:4a7565 a=dtls-id:4a7565
a=dcmap:4 subprotocol="MSRP";label="MSRP" a=dcmap:4 subprotocol="MSRP";label="MSRP"
a=dcsa:4 accept-types:message/cpim text/plain a=dcsa:4 accept-types:message/cpim text/plain
a=dcsa:4 path:msrp://alice.example.com:10001/2s93i93idj;dc a=dcsa:4 path:msrp://alice.example.com:10001/2s93i93idj;dc
Subsequent SDP answer: Subsequent SDP answer:
m=application 10002 UDP/DTLS/SCTP webrtc-datachannel m=application 10002 UDP/DTLS/SCTP webrtc-datachannel
c=IN IP4 10.10.10.2 c=IN IP4 192.0.2.2
a=max-message-size:100000 a=max-message-size:100000
a=sctp-port:5002 a=sctp-port:5002
a=setup:passive a=setup:passive
a=fingerprint:SHA-1 \ a=fingerprint:SHA-1 \
5B:AD:67:B1:3E:82:AC:3B:90:02:B1:DF:12:5D:CA:6B:3F:E5:54:FA 5B:AD:67:B1:3E:82:AC:3B:90:02:B1:DF:12:5D:CA:6B:3F:E5:54:FA
a=dtls-id:532d42 a=dtls-id:532d42
a=dcmap:4 subprotocol="MSRP";label="MSRP" a=dcmap:4 subprotocol="MSRP";label="MSRP"
a=dcsa:4 accept-types:message/cpim text/plain a=dcsa:4 accept-types:message/cpim text/plain
a=dcsa:4 path:msrp://bob.example.com:10002/si438dsaodes;dc a=dcsa:4 path:msrp://bob.example.com:10002/si438dsaodes;dc
skipping to change at page 23, line 49 skipping to change at page 22, line 49
| O/A procedures: | As per Section 5.2 | | O/A procedures: | As per Section 5.2 |
| Mux category: | SPECIAL. See Section 5.1.2.2 | | Mux category: | SPECIAL. See Section 5.1.2.2 |
| Reference: | RFCXXXX | | Reference: | RFCXXXX |
+-----------------------+-------------------------------------------+ +-----------------------+-------------------------------------------+
8.3. New Usage Level 8.3. New Usage Level
This document introduces a new "Data Channel Subprotocol Attribute" This document introduces a new "Data Channel Subprotocol Attribute"
(dcsa) usage level to the SDP to the IANA SDP att-field registry. (dcsa) usage level to the SDP to the IANA SDP att-field registry.
SDP attributes that are defined for use at the dcsa usage level only SDP attributes that are defined for use at the dcsa usage level only
shall use the dcsa usage level when registering the attribute. If SHALL use the dcsa usage level when registering the attribute. If
existing media attributes are used in a datachannel subprotocol existing media attributes are used in a datachannel subprotocol
specific way (Section 5.1.2.1), then a new dcsa usage level MUST be specific way (Section 5.1.2.1), then a new dcsa usage level MUST be
defined for the existing media attribute. Where the SDP attribute is defined for the existing media attribute. Where the SDP attribute is
applicable to a particular subprotocol/s this SHALL also be applicable to a particular subprotocol/s this SHALL also be
registered by indicating the applicable subprotocol identifiers (see registered by indicating the applicable subprotocol identifiers (see
Section 8.1) along with the dcsa usage level. E.g. Section 8.1) along with the dcsa usage level. E.g.
+-----------------------+-------------------------------------------+ +-----------------------+-------------------------------------------+
| ... | ... | | ... | ... |
| Usage level: | dcsa(MSRP) | | Usage level: | dcsa(MSRP) |
skipping to change at page 24, line 25 skipping to change at page 23, line 25
The authors wish to acknowledge the borrowing of ideas from other The authors wish to acknowledge the borrowing of ideas from other
internet drafts by Salvatore Loreto, Gonzalo Camarillo, Peter Dunkley internet drafts by Salvatore Loreto, Gonzalo Camarillo, Peter Dunkley
and Gavin Llewellyn, and to thank Flemming Andreasen, Roni Even, and Gavin Llewellyn, and to thank Flemming Andreasen, Roni Even,
Christian Groves, Gunnar Hellstrom, Christer Holmberg, Paul Kyzivat, Christian Groves, Gunnar Hellstrom, Christer Holmberg, Paul Kyzivat,
Jonathan Lennox, Uwe Rauschenbach and Roman Shpount for their Jonathan Lennox, Uwe Rauschenbach and Roman Shpount for their
invaluable comments. invaluable comments.
10. CHANGE LOG 10. CHANGE LOG
10.1. Changes against 'draft-ietf-mmusic-data-channel-sdpneg-10' 10.1. Changes against 'draft-ietf-mmusic-data-channel-sdpneg-11'
o dcmap-stream-id syntax change to limit size to 5 digits.
o Add missing 'x' prefix to quoted-visible syntax.
o Align SDP offerer and answerer handling when both max-retr and
max-time are present.
o Use of TEST-NET-1 ip addresses in examples.
o Add missing a=dtls-id in one example.
10.2. Changes against 'draft-ietf-mmusic-data-channel-sdpneg-10'
o Removal of the "a=connection" attribute lines from all SDP o Removal of the "a=connection" attribute lines from all SDP
examples. examples.
10.2. Changes against 'draft-ietf-mmusic-data-channel-sdpneg-09' 10.3. Changes against 'draft-ietf-mmusic-data-channel-sdpneg-09'
o In the introduction: o In the introduction:
* Replacement of the sentence "The RTCWeb working group has * Replacement of the sentence "The RTCWeb working group has
defined the concept of bi-directional data channels running on defined the concept of bi-directional data channels running on
top of SCTP/DTLS (SCTP over the Datagram Transport Layer top of SCTP/DTLS (SCTP over the Datagram Transport Layer
Security protocol)" with "The RTCWeb working group has defined Security protocol)" with "The RTCWeb working group has defined
the concept of bi-directional data channels running on top of the concept of bi-directional data channels running on top of
the Stream Control Transmission Protocol (SCTP)". the Stream Control Transmission Protocol (SCTP)".
* Addition of following sentences to the second paragraph: "These * Addition of following sentences to the second paragraph: "These
procedures are based on generic SDP offer/answer negotiation procedures are based on generic SDP offer/answer negotiation
rules for SCTP based media transport as specified in rules for SCTP based media transport as specified in
[I-D.ietf-mmusic-sctp-sdp] for the SDP "m" line proto values [I-D.ietf-mmusic-sctp-sdp] for the SDP "m" line proto values
UDP/DTLS/SCTP and TCP/DTLS/SCTP. In future data channels could UDP/DTLS/SCTP and TCP/DTLS/SCTP. In the future, data channels
be defined over other SCTP based protocols, such as SCTP over could be defined over other SCTP based protocols, such as SCTP
IP. However, corresponding potential other "m" line proto over IP. However, corresponding potential other "m" line proto
values are not considered in this document." values are not considered in this document."
o Replacement of "DTLS connection" with "DTLS association" o Replacement of "DTLS connection" with "DTLS association"
throughout the document. throughout the document.
o In sections Section 5.1.1.2 and Section 5.1.2.2 removal of the o In sections Section 5.1.1.2 and Section 5.1.2.2 removal of the
sentences "This document also does not specify multiplexing rules sentences "This document also does not specify multiplexing rules
for this attribute for SCTP or SCTP/DTLS proto values". for this attribute for SCTP or SCTP/DTLS proto values".
o In the text related to "Subsequent SDP answer" in section o In the text related to "Subsequent SDP answer" in section
skipping to change at page 25, line 23 skipping to change at page 24, line 37
o In the text after the second SDP answer in section Section 6 o In the text after the second SDP answer in section Section 6
replacement of "... (after SCTP/DTLS association is setup)" with replacement of "... (after SCTP/DTLS association is setup)" with
"... (after the SCTP association is set up)". "... (after the SCTP association is set up)".
o Addition of [I-D.ietf-mmusic-dtls-sdp] to the list of informative o Addition of [I-D.ietf-mmusic-dtls-sdp] to the list of informative
references. references.
o Addition of "a=dtls-id" attribute lines to the SDP offer/answer o Addition of "a=dtls-id" attribute lines to the SDP offer/answer
examples in Section 6. examples in Section 6.
10.3. Changes against 'draft-ietf-mmusic-data-channel-sdpneg-08' 10.4. Changes against 'draft-ietf-mmusic-data-channel-sdpneg-08'
o Addition of definition of "data channel subprotocol" to Section 3 o Addition of definition of "data channel subprotocol" to Section 3
as proposed on the MMUSIC list, https://www.ietf.org/mail- as proposed on the MMUSIC list, https://www.ietf.org/mail-
archive/web/mmusic/current/msg15827.html. archive/web/mmusic/current/msg15827.html.
o Addition of [I-D.ietf-mmusic-rfc4566bis] to list of normative o Addition of [I-D.ietf-mmusic-rfc4566bis] to list of normative
references. references.
o Updates of tables in Section 8.2.1 and Section 8.2.2 as per o Updates of tables in Section 8.2.1 and Section 8.2.2 as per
section 8.2.4 of [I-D.ietf-mmusic-rfc4566bis]. section 8.2.4 of [I-D.ietf-mmusic-rfc4566bis].
o Addition of new Section 8.3. o Addition of new Section 8.3.
10.4. Changes against 'draft-ietf-mmusic-data-channel-sdpneg-07' 10.5. Changes against 'draft-ietf-mmusic-data-channel-sdpneg-07'
o Addition of two new paragraphs to Section 5.1.2.1 regarding o Addition of two new paragraphs to Section 5.1.2.1 regarding
subprotocol attribute relationship with transport protocol. subprotocol attribute relationship with transport protocol.
o Addition of a note to Section 8.1 regarding subprotocols o Addition of a note to Section 8.1 regarding subprotocols
simultaneously defined for data channel and Websocket usage. simultaneously defined for data channel and Websocket usage.
o Addition of two further SDP offer/answer considerations to o Addition of two further SDP offer/answer considerations to
Section 5.2.5 regarding unknown subprotocol attributes and known Section 5.2.5 regarding unknown subprotocol attributes and known
subprotocol attributes with unknown data channel transport related subprotocol attributes with unknown data channel transport related
semantic. semantic.
10.5. Changes against 'draft-ietf-mmusic-data-channel-sdpneg-06' 10.6. Changes against 'draft-ietf-mmusic-data-channel-sdpneg-06'
o Changes addressing Christian Groves's WGLC review comments raised o Changes addressing Christian Groves's WGLC review comments raised
in http://www.ietf.org/mail-archive/web/mmusic/current/ in http://www.ietf.org/mail-archive/web/mmusic/current/
msg15357.html and http://www.ietf.org/mail- msg15357.html and http://www.ietf.org/mail-
archive/web/mmusic/current/msg15359.html. archive/web/mmusic/current/msg15359.html.
10.6. Changes against 'draft-ietf-mmusic-data-channel-sdpneg-05' 10.7. Changes against 'draft-ietf-mmusic-data-channel-sdpneg-05'
o In IANA registration Section 8.2.1 and Section 8.2.2 replacement o In IANA registration Section 8.2.1 and Section 8.2.2 replacement
of contact name and e-mail address with "MMUSIC Chairs" and of contact name and e-mail address with "MMUSIC Chairs" and
"mmusic-chairs@ietf.org". "mmusic-chairs@ietf.org".
o In Section 5.1.2.1 replacement of "Thus in the example above, the o In Section 5.1.2.1 replacement of "Thus in the example above, the
original attribute line "a=accept- types:text/plain" is original attribute line "a=accept- types:text/plain" is
represented by the attribute line "a=dcsa:2 accept-types:text/ represented by the attribute line "a=dcsa:2 accept-types:text/
plain", which specifies that this instance of MSRP being plain", which specifies that this instance of MSRP being
transported on the SCTP association using the data channel with transported on the SCTP association using the data channel with
skipping to change at page 27, line 5 skipping to change at page 26, line 14
o Move of the last but one paragraph of Section 5.1.2.1 starting o Move of the last but one paragraph of Section 5.1.2.1 starting
with "The same syntax applies to ..." right in front of the formal with "The same syntax applies to ..." right in front of the formal
syntax definition of the "dcsa" attribute. syntax definition of the "dcsa" attribute.
o Modifications of the text in Section 5.1.1.2 and Section 5.1.2.2 o Modifications of the text in Section 5.1.1.2 and Section 5.1.2.2
in order not to explicitly restrict usage of the "a=dcmap:" and in order not to explicitly restrict usage of the "a=dcmap:" and
"a=dcsa:" attributes to "m" lines with proto values "UDP/DTLS/ "a=dcsa:" attributes to "m" lines with proto values "UDP/DTLS/
SCTP" or "TCP/DTLS/SCTP". SCTP" or "TCP/DTLS/SCTP".
10.7. Changes against 'draft-ietf-mmusic-data-channel-sdpneg-04' 10.8. Changes against 'draft-ietf-mmusic-data-channel-sdpneg-04'
o In Section 5.1.1.5 the first (and only) paragraph was "The o In Section 5.1.1.5 the first (and only) paragraph was "The
'subprotocol' parameter indicates which protocol the client 'subprotocol' parameter indicates which protocol the client
expects to exchange via the channel. 'Subprotocol' is an optional expects to exchange via the channel. 'Subprotocol' is an optional
parameter. If the 'subprotocol' parameter is not present, then parameter. If the 'subprotocol' parameter is not present, then
its value defaults to the empty string." Replacement of this its value defaults to the empty string." Replacement of this
paragraph with following two paragraphs: paragraph with following two paragraphs:
* The 'subprotocol' parameter indicates which protocol the client * The 'subprotocol' parameter indicates which protocol the client
expects to exchange via the channel. This parameter maps to expects to exchange via the channel. This parameter maps to
skipping to change at page 27, line 46 skipping to change at page 27, line 8
o Addition of new Section 5.1.1.2 describing the mux category of the o Addition of new Section 5.1.1.2 describing the mux category of the
dcmap SDP attribute. This section and the new "a=dcsa:" attribute dcmap SDP attribute. This section and the new "a=dcsa:" attribute
related mux category section are similar to the "Mux Category" related mux category section are similar to the "Mux Category"
sections of the "a=sctp-port:" and "a=max-message-size:" sections of the "a=sctp-port:" and "a=max-message-size:"
attributes in [I-D.ietf-mmusic-sctp-sdp]. attributes in [I-D.ietf-mmusic-sctp-sdp].
o Addition of new Section 5.1.2.2 describing the mux category of the o Addition of new Section 5.1.2.2 describing the mux category of the
dcsa SDP attribute. dcsa SDP attribute.
10.8. Changes against 'draft-ietf-mmusic-data-channel-sdpneg-03' 10.9. Changes against 'draft-ietf-mmusic-data-channel-sdpneg-03'
o In Section 1 replacement of "RTCWeb leaves it open for other o In Section 1 replacement of "RTCWeb leaves it open for other
applications to use data channels and its in-band DCEP or out-of- applications to use data channels and its in-band DCEP or out-of-
band non-DCEP protocols for creating them" with "... to use data band non-DCEP protocols for creating them" with "... to use data
channels and its in-band DCEP or other in-band or out-of-band channels and its in-band DCEP or other in-band or out-of-band
protocols for creating them". Additionally replacement of "In protocols for creating them". Additionally replacement of "In
particular, the SDP offer generated by the application includes no particular, the SDP offer generated by the application includes no
channel-specific information" with "... generated by the RTCweb channel-specific information" with "... generated by the RTCweb
data channel stack includes no channel-specific information". data channel stack includes no channel-specific information".
skipping to change at page 29, line 8 skipping to change at page 28, line 17
o In Section 5.2.1 replacement of "However, an SDP offer/answer o In Section 5.2.1 replacement of "However, an SDP offer/answer
exchange MUST NOT be initiated if the associated SCTP stream is exchange MUST NOT be initiated if the associated SCTP stream is
already negotiated via DCEP" with "However, an SCTP stream MUST already negotiated via DCEP" with "However, an SCTP stream MUST
NOT be referenced in a dcmap or dcsa attribute of an SDP offer/ NOT be referenced in a dcmap or dcsa attribute of an SDP offer/
answer exchange if the associated SCTP stream has already been answer exchange if the associated SCTP stream has already been
negotiated via DCEP". negotiated via DCEP".
o In the examples in Section 6 addition of the previously missing o In the examples in Section 6 addition of the previously missing
colons to the "a=sctp-port" attribute lines. colons to the "a=sctp-port" attribute lines.
10.9. Changes against 'draft-ietf-mmusic-data-channel-sdpneg-02' 10.10. Changes against 'draft-ietf-mmusic-data-channel-sdpneg-02'
o Move of reference [I-D.ietf-rtcweb-jsep] from the list of o Move of reference [I-D.ietf-rtcweb-jsep] from the list of
normative references to the list of informative references. normative references to the list of informative references.
o Addition of [IANA-SDP-Parameters] to the list of informative o Addition of [IANA-SDP-Parameters] to the list of informative
references and addition of following two sentences to the first references and addition of following two sentences to the first
paragraph after the ABNF definition: "Note however that not all paragraph after the ABNF definition: "Note however that not all
SDP attributes are suitable as "a=dcsa:" parameter. SDP attributes are suitable as "a=dcsa:" parameter.
[IANA-SDP-Parameters] contains the lists of IANA registered [IANA-SDP-Parameters] contains the lists of IANA registered
session and media level or media level only SDP attributes." session and media level or media level only SDP attributes."
skipping to change at page 30, line 10 skipping to change at page 29, line 19
a=dcmap". a=dcmap".
o Move of reference [WebRtcAPI] from list of normative references to o Move of reference [WebRtcAPI] from list of normative references to
list of informative references. list of informative references.
o Removal of almost all text parts, which discussed JavaScript or o Removal of almost all text parts, which discussed JavaScript or
other API specific aspects. Such API specific aspects were mainly other API specific aspects. Such API specific aspects were mainly
discussed in sub-sections of Section 5 and Section 5 of draft- discussed in sub-sections of Section 5 and Section 5 of draft-
ietf-mmusic-data-channel-sdpneg-02. ietf-mmusic-data-channel-sdpneg-02.
10.10. Changes against 'draft-ietf-mmusic-data-channel-sdpneg-01' 10.11. Changes against 'draft-ietf-mmusic-data-channel-sdpneg-01'
o New Section 4 regarding applicability to SDP offer/answer only. o New Section 4 regarding applicability to SDP offer/answer only.
o Addition of new Section 8.1 "Subprotocol identifiers" as o Addition of new Section 8.1 "Subprotocol identifiers" as
subsection of the "IANA Considerations" related Section 8. Also subsection of the "IANA Considerations" related Section 8. Also
removal of the temporary note "To be completed. As [I-D.ietf- removal of the temporary note "To be completed. As [I-D.ietf-
rtcweb-data-protocol] this document should refer to IANA's rtcweb-data-protocol] this document should refer to IANA's
WebSocket Subprotocol Name Registry defined in [RFC6455]." WebSocket Subprotocol Name Registry defined in [RFC6455]."
o In Section 5.2.2: o In Section 5.2.2:
skipping to change at page 31, line 11 skipping to change at page 30, line 22
o In Section 5.2.5 the description of bullet point "SDP offer has no o In Section 5.2.5 the description of bullet point "SDP offer has no
a=dcmap attributes - Initial SDP offer:" was "Initial SDP offer: a=dcmap attributes - Initial SDP offer:" was "Initial SDP offer:
No data channel negotiated yet." Replacement of this description No data channel negotiated yet." Replacement of this description
with "Initial SDP offer: No data channel is negotiated yet. The with "Initial SDP offer: No data channel is negotiated yet. The
DTLS connection and SCTP association is negotiated and, if agreed, DTLS connection and SCTP association is negotiated and, if agreed,
established as per [I-D.ietf-mmusic-sctp-sdp]." established as per [I-D.ietf-mmusic-sctp-sdp]."
o In Section 5.2.5 in both bullet points related to "Subsequent SDP o In Section 5.2.5 in both bullet points related to "Subsequent SDP
offer" and "Subsequent SDP answer" replacement of "All the offer" and "Subsequent SDP answer" replacement of "All the
externally negotiated data channels must be closed now." with "All externally negotiated data channels must be closed now." with "All
the externally negotiated data channels are expected be closed the externally negotiated data channels are expected to be closed
now.". now.".
o In Appendix A.2.2's sixth paragraph beginning with "[ASSUMPTION]" o In Appendix A.2.2's sixth paragraph beginning with "[ASSUMPTION]"
replacement of the two occurrences of "must" with "MUST". replacement of the two occurrences of "must" with "MUST".
o In Section 5.1.1.1 in the definition of the ABNF rule "dcmap-opt" o In Section 5.1.1.1 in the definition of the ABNF rule "dcmap-opt"
there was a comment saying that "Either only maxretr-opt or there was a comment saying that "Either only maxretr-opt or
maxtime-opt is present. Both MUST not be present." Removal of maxtime-opt is present. Both MUST not be present." Removal of
the second normative sentence and instead addition of following the second normative sentence and instead addition of following
new paragraph to the end of this section: "Within an 'a=dcmap' new paragraph to the end of this section: "Within an 'a=dcmap'
skipping to change at page 32, line 15 skipping to change at page 31, line 26
* In the last but one paragraph replacement of "must" with "The * In the last but one paragraph replacement of "must" with "The
application MUST also close...". application MUST also close...".
o In Section 5.1.2 addition of following note after the formal o In Section 5.1.2 addition of following note after the formal
definition of the 'a=dcsa' attribute: "Note that the above definition of the 'a=dcsa' attribute: "Note that the above
reference to RFC 4566 defines were the attribute definition can be reference to RFC 4566 defines were the attribute definition can be
found; it does not provide any limitation on support of attributes found; it does not provide any limitation on support of attributes
defined in other documents in accordance with this attribute defined in other documents in accordance with this attribute
definition." definition."
10.11. Changes against 'draft-ietf-mmusic-data-channel-sdpneg-00' 10.12. Changes against 'draft-ietf-mmusic-data-channel-sdpneg-00'
o In Section 3 "WebRTC data channel" was defined as "A bidirectional o In Section 3 "WebRTC data channel" was defined as "A bidirectional
channel consisting of paired SCTP outbound and inbound streams." channel consisting of paired SCTP outbound and inbound streams."
Replacement of this definition with "Data channel: A WebRTC data Replacement of this definition with "Data channel: A WebRTC data
channel as specified in [I-D.ietf-rtcweb-data-channel]", and channel as specified in [I-D.ietf-rtcweb-data-channel]", and
consistent usage of "data channel" in the remainder of the consistent usage of "data channel" in the remainder of the
document including the document's headline." document including the document's headline."
o In Section 5 removal of following note: 'OPEN ISSUE: The syntax in o In Section 5 removal of following note: 'OPEN ISSUE: The syntax in
[I-D.ietf-mmusic-sctp-sdp] may change as that document progresses. [I-D.ietf-mmusic-sctp-sdp] may change as that document progresses.
skipping to change at page 35, line 5 skipping to change at page 34, line 11
to handle cases where a successful SDP answer is not received, in to handle cases where a successful SDP answer is not received, in
which case the state of the session SHOULD be kept per the last which case the state of the session SHOULD be kept per the last
successful SDP offer/answer." successful SDP offer/answer."
o Although dedicated to "a=dcmap" and "a=dcsa" SDP syntax aspects o Although dedicated to "a=dcmap" and "a=dcsa" SDP syntax aspects
Section 5.1.1 contained already procedural descriptions related to Section 5.1.1 contained already procedural descriptions related to
data channel reliability negotiation. Creation of new data channel reliability negotiation. Creation of new
Section 5.2.2 and moval of reliability negotiation related text to Section 5.2.2 and moval of reliability negotiation related text to
this new section. this new section.
10.12. Changes against 'draft-ejzak-mmusic-data-channel-sdpneg-02' 10.13. Changes against 'draft-ejzak-mmusic-data-channel-sdpneg-02'
o Removal of note "[ACTION ITEM]" from section "subprotocol o Removal of note "[ACTION ITEM]" from section "subprotocol
parameter". As [I-D.ietf-rtcweb-data-protocol] this document parameter". As [I-D.ietf-rtcweb-data-protocol] this document
should refer to IANA's WebSocket Subprotocol Name Registry defined should refer to IANA's WebSocket Subprotocol Name Registry defined
in [RFC6455]. in [RFC6455].
o In whole document, replacement of "unreliable" with "partially o In whole document, replacement of "unreliable" with "partially
reliable", which is used in [I-D.ietf-rtcweb-data-channel] and in reliable", which is used in [I-D.ietf-rtcweb-data-channel] and in
[I-D.ietf-rtcweb-data-protocol] in most places. [I-D.ietf-rtcweb-data-protocol] in most places.
skipping to change at page 36, line 7 skipping to change at page 35, line 14
o In the "Examples" section, in the first two SDP offer examples in o In the "Examples" section, in the first two SDP offer examples in
the a=dcmap attribute lines 'label="BGCP"' was replaced with the a=dcmap attribute lines 'label="BGCP"' was replaced with
'label="BFCP"'. 'label="BFCP"'.
o In all examples, the "m" line proto value "DTLS/SCTP" was replaced o In all examples, the "m" line proto value "DTLS/SCTP" was replaced
with "UDP/DTLS/SCTP" and the "a=fmtp" attribute lines were with "UDP/DTLS/SCTP" and the "a=fmtp" attribute lines were
replaced with "a=max-message-size" attribute lines, as per draft- replaced with "a=max-message-size" attribute lines, as per draft-
ietf-mmusic-sctp-sdp-12. ietf-mmusic-sctp-sdp-12.
10.13. Changes against '-01' 10.14. Changes against '-01'
o Formal syntax for dcmap and dcsa attribute lines. o Formal syntax for dcmap and dcsa attribute lines.
o Making subprotocol as an optional parameter in dcmap. o Making subprotocol as an optional parameter in dcmap.
o Specifying disallowed parameter combinations for max-time and max- o Specifying disallowed parameter combinations for max-time and max-
retr. retr.
o Clarifications on WebRTC data channel close procedures. o Clarifications on WebRTC data channel close procedures.
10.14. Changes against '-00' 10.15. Changes against '-00'
o Revisions to identify difference between internal and external o Revisions to identify difference between internal and external
negotiation and their usage. negotiation and their usage.
o Introduction of more generic terminology, e.g. "application" o Introduction of more generic terminology, e.g. "application"
instead of "browser". instead of "browser".
o Clarification of how "max-retr and max-time affect the usage of o Clarification of how "max-retr and max-time affect the usage of
unreliable and reliable WebRTC data channels. unreliable and reliable WebRTC data channels.
skipping to change at page 37, line 30 skipping to change at page 36, line 34
[I-D.ietf-rtcweb-data-channel] [I-D.ietf-rtcweb-data-channel]
Jesup, R., Loreto, S., and M. Tuexen, "WebRTC Data Jesup, R., Loreto, S., and M. Tuexen, "WebRTC Data
Channels", draft-ietf-rtcweb-data-channel-13 (work in Channels", draft-ietf-rtcweb-data-channel-13 (work in
progress), January 2015. progress), January 2015.
[I-D.ietf-mmusic-sctp-sdp] [I-D.ietf-mmusic-sctp-sdp]
Holmberg, C., Shpount, R., Loreto, S., and G. Camarillo, Holmberg, C., Shpount, R., Loreto, S., and G. Camarillo,
"Session Description Protocol (SDP) Offer/Answer "Session Description Protocol (SDP) Offer/Answer
Procedures For Stream Control Transmission Protocol (SCTP) Procedures For Stream Control Transmission Protocol (SCTP)
over Datagram Transport Layer Security (DTLS) Transport.", over Datagram Transport Layer Security (DTLS) Transport.",
draft-ietf-mmusic-sctp-sdp-20 (work in progress), December draft-ietf-mmusic-sctp-sdp-25 (work in progress), March
2016. 2017.
[I-D.ietf-mmusic-sdp-mux-attributes] [I-D.ietf-mmusic-sdp-mux-attributes]
Nandakumar, S., "A Framework for SDP Attributes when Nandakumar, S., "A Framework for SDP Attributes when
Multiplexing", draft-ietf-mmusic-sdp-mux-attributes-16 Multiplexing", draft-ietf-mmusic-sdp-mux-attributes-16
(work in progress), December 2016. (work in progress), December 2016.
11.2. Informative References 11.2. Informative References
[I-D.ietf-rtcweb-data-protocol] [I-D.ietf-rtcweb-data-protocol]
Jesup, R., Loreto, S., and M. Tuexen, "WebRTC Data Channel Jesup, R., Loreto, S., and M. Tuexen, "WebRTC Data Channel
Establishment Protocol", draft-ietf-rtcweb-data- Establishment Protocol", draft-ietf-rtcweb-data-
protocol-09 (work in progress), January 2015. protocol-09 (work in progress), January 2015.
[I-D.ietf-mmusic-dtls-sdp] [I-D.ietf-mmusic-dtls-sdp]
Holmberg, C. and R. Shpount, "Using the SDP Offer/Answer Holmberg, C. and R. Shpount, "Using the SDP Offer/Answer
Mechanism for DTLS", draft-ietf-mmusic-dtls-sdp-15 (work Mechanism for DTLS", draft-ietf-mmusic-dtls-sdp-22 (work
in progress), October 2016. in progress), March 2017.
[RFC4960] Stewart, R., Ed., "Stream Control Transmission Protocol", [RFC4960] Stewart, R., Ed., "Stream Control Transmission Protocol",
RFC 4960, DOI 10.17487/RFC4960, September 2007, RFC 4960, DOI 10.17487/RFC4960, September 2007,
<http://www.rfc-editor.org/info/rfc4960>. <http://www.rfc-editor.org/info/rfc4960>.
[IANA-SDP-Parameters] [IANA-SDP-Parameters]
"Session Description Protocol (SDP) Parameters", Internet "Session Description Protocol (SDP) Parameters", Internet
Assigned Numbers Authority Protocol Assignments Session Assigned Numbers Authority Protocol Assignments Session
Description Protocol (SDP) Parameters, Description Protocol (SDP) Parameters,
<http://www.iana.org/assignments/sdp-parameters/ <http://www.iana.org/assignments/sdp-parameters/
skipping to change at page 38, line 39 skipping to change at page 37, line 43
priority). The application also specifies if it wants to make use of priority). The application also specifies if it wants to make use of
the negotiation using the DCEP [I-D.ietf-rtcweb-data-protocol], or if the negotiation using the DCEP [I-D.ietf-rtcweb-data-protocol], or if
the application intends to negotiate data channels using the SDP the application intends to negotiate data channels using the SDP
offer/answer protocol. offer/answer protocol.
In any case, the SDP offer generated by the application is per In any case, the SDP offer generated by the application is per
[I-D.ietf-mmusic-sctp-sdp]. In brief, it contains one "m" line for [I-D.ietf-mmusic-sctp-sdp]. In brief, it contains one "m" line for
the SCTP association on top of which data channels will run: the SCTP association on top of which data channels will run:
m=application 54111 UDP/DTLS/SCTP webrtc-datachannel m=application 54111 UDP/DTLS/SCTP webrtc-datachannel
c=IN IP4 79.97.215.79 c=IN IP4 10.10.10.1
a=max-message-size:100000 a=max-message-size:100000
a=sctp-port:5000 a=sctp-port:5000
a=dtls-id:abcdef1234567
a=setup:actpass a=setup:actpass
a=fingerprint:SHA-1 \ a=fingerprint:SHA-1 \
4A:AD:B9:B1:3F:82:18:3B:54:02:12:DF:3E:5D:49:6B:19:E5:7C:AB 4A:AD:B9:B1:3F:82:18:3B:54:02:12:DF:3E:5D:49:6B:19:E5:7C:AB
Note: A WebRTC application will only use "m" line format "webrtc- Note: A WebRTC application will only use "m" line format "webrtc-
datachannel", and will not use other formats in the "m" line for datachannel", and will not use other formats in the "m" line for
other protocols such as t38. [I-D.ietf-mmusic-sctp-sdp] supports other protocols such as t38. [I-D.ietf-mmusic-sctp-sdp] supports
only one SCTP association to be established on top of a DTLS only one SCTP association to be established on top of a DTLS
association. association.
Note: The above SDP media description does not contain any channel- Note: The above SDP media description does not contain any channel-
specific information. specific information.
A.1. Stream Identifier Numbering A.1. Stream Identifier Numbering
Independently from the requested type of negotiation, the application Independently from the requested type of negotiation, the application
creating a data channel can either pass to the data channel stack the creating a data channel can either pass the stream identifier to the
stream identifier to assign to the data channel or else let the data data channel stack to assign to the data channel or else let the data
channel stack pick one identifier from the unused ones. channel stack pick one identifier from the unused ones.
To avoid glare situations, each endpoint can moreover own an To avoid glare situations, each endpoint can moreover own an
exclusive set of stream identifiers, in which case an endpoint can exclusive set of stream identifiers, in which case an endpoint can
only create a data channel with a stream identifier it owns. only create a data channel with a stream identifier it owns.
Which set of stream identifiers is owned by which endpoint is Which set of stream identifiers is owned by which endpoint is
determined by convention or other means. determined by convention or other means.
For data channels negotiated with the DCEP, one endpoint owns by Note:For data channels negotiated with the DCEP, one endpoint owns
convention the even stream identifiers, whereas the other owns the by convention the even stream identifiers, whereas the other owns
odd stream identifiers, as defined in the odd stream identifiers, as defined in
[I-D.ietf-rtcweb-data-protocol]. [I-D.ietf-rtcweb-data-protocol].
For data channels negotiated via some protocol different from Note:For data channels negotiated via some protocol different from
DCEP, no convention is defined by default. DCEP, no convention is defined by default.
A.2. Generic Data Channel Negotiation Not Using DCEP A.2. Generic Data Channel Negotiation Not Using DCEP
A.2.1. Overview A.2.1. Overview
DCEP negotiation only provides for negotiation of data channel DCEP negotiation only provides for negotiation of data channel
transport parameters and does not provide for negotiation of transport parameters and does not provide for negotiation of
subprotocol specific parameters. DCEP-less data channel negotiation subprotocol specific parameters. DCEP-less data channel negotiation
can be defined to allow negotiation of parameters beyond those can be defined to allow negotiation of parameters beyond those
 End of changes. 61 change blocks. 
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